After a lot of cursing regarding the Keypad library - the people who wrote it, it didn't seem to occur to them to have a simple 'is a key down' test, which is pretty helpful if you are programming games, I've got the keypad working. I might just chuck the keypad library and access the controls directly, rather like the LCD4884 library it is a bit limited.
I've also added the sound, which worked very well. The thing now beeps at me if I leave it alone though, Microvision carts do this to warn against battery usage.
So in BlockBuster you can now set the parameters and start the game up, of course you can't play it because I have done the pot (yet).
I always found Block Buster really difficult anyway, even on a real Microvision.